Remove support for upgrading extensions from "unpackaged" state.

Andres Freund pointed out that allowing non-superusers to run
"CREATE EXTENSION ... FROM unpackaged" has security risks, since
the unpackaged-to-1.0 scripts don't try to verify that the existing
objects they're modifying are what they expect.  Just attaching such
objects to an extension doesn't seem too dangerous, but some of them
do more than that.

We could have resolved this, perhaps, by still requiring superuser
privilege to use the FROM option.  However, it's fair to ask just what
we're accomplishing by continuing to lug the unpackaged-to-1.0 scripts
forward.  None of them have received any real testing since 9.1 days,
so they may not even work anymore (even assuming that one could still
load the previous "loose" object definitions into a v13 database).
And an installation that's trying to go from pre-9.1 to v13 or later
in one jump is going to have worse compatibility problems than whether
there's a trivial way to convert their contrib modules into extension
style.

Hence, let's just drop both those scripts and the core-code support
for "CREATE EXTENSION ... FROM".

Discussion: https://postgr.es/m/20200213233015.r6rnubcvl4egdh5r@alap3.anarazel.de

3 files changed, 2 insertions, 31 deletions

diff --git a/contrib/xml2/Makefile b/contrib/xml2/Makefile
index 6ca2b7c8628..0d703fe0e8f 100644
--- a/contrib/xml2/Makefile
+++ b/contrib/xml2/Makefile
@@ -7,7 +7,7 @@ OBJS = \
 	xslt_proc.o
 
 EXTENSION = xml2
-DATA = xml2--1.1.sql xml2--1.0--1.1.sql xml2--unpackaged--1.0.sql
+DATA = xml2--1.1.sql xml2--1.0--1.1.sql
 PGFILEDESC = "xml2 - XPath querying and XSLT"
 
 REGRESS = xml2
diff --git a/contrib/xml2/xml2--unpackaged--1.0.sql b/contrib/xml2/xml2--unpackaged--1.0.sql
deleted file mode 100644
index 8badef3079b..00000000000
--- a/contrib/xml2/xml2--unpackaged--1.0.sql
+++ /dev/null
@@ -1,29 +0,0 @@
-/* contrib/xml2/xml2--unpackaged--1.0.sql */
-
--- complain if script is sourced in psql, rather than via CREATE EXTENSION
-\echo Use "CREATE EXTENSION xml2 FROM unpackaged" to load this file. \quit
-
-ALTER EXTENSION xml2 ADD function xslt_process(text,text);
-ALTER EXTENSION xml2 ADD function xslt_process(text,text,text);
-ALTER EXTENSION xml2 ADD function xpath_table(text,text,text,text,text);
-ALTER EXTENSION xml2 ADD function xpath_nodeset(text,text,text);
-ALTER EXTENSION xml2 ADD function xpath_nodeset(text,text);
-ALTER EXTENSION xml2 ADD function xpath_list(text,text);
-ALTER EXTENSION xml2 ADD function xpath_list(text,text,text);
-ALTER EXTENSION xml2 ADD function xpath_bool(text,text);
-ALTER EXTENSION xml2 ADD function xpath_number(text,text);
-ALTER EXTENSION xml2 ADD function xpath_nodeset(text,text,text,text);
-ALTER EXTENSION xml2 ADD function xpath_string(text,text);
-ALTER EXTENSION xml2 ADD function xml_encode_special_chars(text);
-ALTER EXTENSION xml2 ADD function xml_valid(text);
-
--- xml_valid is now an alias for core xml_is_well_formed()
-
-CREATE OR REPLACE FUNCTION xml_valid(text) RETURNS bool
-AS 'xml_is_well_formed'
-LANGUAGE INTERNAL STRICT STABLE;
-
--- xml_is_well_formed is now in core, not needed in extension.
--- be careful to drop extension's copy not core's.
-
-DROP FUNCTION @extschema@.xml_is_well_formed(text);
diff --git a/contrib/xml2/xml2.control b/contrib/xml2/xml2.control
index 91e6547f015..ba2c0599a37 100644
--- a/contrib/xml2/xml2.control
+++ b/contrib/xml2/xml2.control
@@ -2,5 +2,5 @@
 comment = 'XPath querying and XSLT'
 default_version = '1.1'
 module_pathname = '$libdir/pgxml'
-# non-relocatable because xml2--unpackaged--1.0.sql needs to use @extschema@
+# XXX do we still need this to be non-relocatable?
 relocatable = false